Blastomycosis is a disease of humans and animals caused by inhalation of airborne spores from Blastomyces dermatitidis, a dimorphic fungus found in soil. The spectrum of clinical manifestations of blastomycosis includes acute pulmonary disease, subacute and chronic pulmonary disease (most common presentations), and disseminated extrapulmonary disease (cutaneous manifestations are most common, followed by involvement of the bone, the genitourinary tract, and central nervous system). Although the disease is not nationally notifiable, it was designated a reportable condition in Wisconsin in 1984 following two large outbreaks. This report summarizes information about cases of blastomycosis reported in Wisconsin during 1986-1995 and highlights the importance of surveillance for blastomycosis in areas with endemic disease.